Materials Literature
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Reflectance anisotropy spectrometry is used to study the electronic properties of sulfide-passivated GaAs. The optical technique allows measurement of the Fermi-level displacement at the surface in situ, while the sample is immersed into a sulfide solution. The kinetics of the process was found to be very sensitive to…
SiC‐ and Al 2 O 3 ‐platelet‐reinforced mullite‐matrix composites were fabricated by both conventional powder processing and a pressure filtration route with constant filtration rate. Consolidation during the pressure filtration experiment was monitored as a function of time with respect to actual pressing stages. The…
This paper compares the mineralogy and chemistry of clay minerals in sediments from various depths and positions in Abert Lake and surrounding playa with those of the weathered materials entering the lake in order to reveal the nature and extent of post-depositional mineralogical modification. Analytical electron micr…
Zr–Hf interdiffusions were carried out at 1350° to 1520°C for polycrystalline tetragonal solid solutions of 14CeO 2 ·86(Zr 1‐ x Hf x )O 2 with X = 0.02 and 0.10. Lattice and grain‐boundary interdiffusion parameters were calculated from the concentration distributions by using Oishi and Ichimura's equation. Lattice int…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfrared spectra of boron atom-water molecule reaction products trapped in solid argonLester Andrews and Thomas R. BurkholderCite this: J. Phys. Chem. 1991, 95, 22, 8554–8560Publication Date (Print):October 1, 1991Publication History Published online1 May 2002Published iniss…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic behavior of noble metal/reducible oxide materials for low-temperature carbon monoxide oxidation. 2. Surface characterization of gold/manganese oxideSteven D. Gardner, Gar B. Hoflund, Mark R. Davidson, Herbert A. Laitinen, David R. Schryer, and Billy T. UpchurchCite…
Mullite ceramics were fabricated according to the recently developed reaction‐bonded Al 2 O 3 (RBAO) technology. Green compacts consisting of mechanically alloyed Al, SiC, and Al 2 O 3 were heat‐treated in two steps. During the first hold at 1200°C, Al and SiC were oxidized to form Al 2 O 3 and SiO 2 . On further heat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and spectroscopic and magnetic properties of a unique diamagnetic binuclear .mu.-oxo vanadium(IV) complex. Crystal structure of [(tpa)VO(.mu.-O)VO(tpa)](ClO4)2 (tpa = tris(2-pyridylmethyl)amine)Hans Toftlund, Sine Larsen, and Keith S. MurrayCite this: Inorg. Chem.…
Communication: The effective conjugation length of poly(phenylenevinylene) an important conducting polymer, can be estimated by extrapolation of the results of UV/VIS/NIR studies of the radical anions and dianions of the soluble, well‐characterized oligo(phenylenevinylene)s shown in the figure. This information, in tu…
Several approaches were used to study the role of GroEL, the prototype chaperonin, in the nitrogen fixation (nif) system. An Escherichia coli groEL mutant transformed with the Klebsiella pneumoniae nif gene cluster accumulated very low to nondetectable levels of nitrogenase components compared with the isogenic wild-t…
Diphasic gels with Al/Si atomic ratios of 6/1, 3.1/1, 3/1, 2/1, and 1/1 were used to study the effect of precursor composition on mullite formation process and the resulting microstructure. Mullite formation initiated at about 1300°C for all samples, with only some slight differences in temperatures. The mullite forma…
Machine learning (ML) is transforming all areas of science. The complex and time-consuming calculations in molecular simulations are particularly suitable for an ML revolution and have already been profoundly affected by the application of existing ML ...Read More
The contrast of dislocations in icosahedral quasicrystals observed by transmission electron microscopy is discussed in the framework of the kinematical theory of electron diffraction. It is found that, owing to the special structural features of dislocations in quasiperiodic lattices, there are two basically different…
The solubility limit of α'‐SiAION solid solutions on the Si 3 N 4 ─YN:3AIN composition join in the system Si 3 N 4 ─YN─AIN has been determined at 1800°C. The end members of these solid solutions are Y 0.43 Si 10.7 Al 1.3 N 16 and Y 0.8 Si 9.6 Al 2.4 N 16 . Unit‐cell dimensions of the α'‐SiAION solid solutions in the s…
Abstract On the basis of a two‐sublattice model, the temperature dependent magnetic properties of the intermetallic compounds R 2 Fe 17 C (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Lu) are analyzed using the molecular‐field theory. The results of the analysis show that the molecular‐field coefficients n RF are rather se…
Abstract A hot‐stage unit, operating over the temperature range from ambient to 1000°C has been used to study the combustion of black powder. Direct observation of heating of mixtures was supplemented by 35‐mm photomicrography. Results are presented for black powder supplied and mixture prepared in the laboratory.
We have compared the mechanical properties of wool fibers from three different breeds of sheep, Lincoln, Chokla, and Merino. The tensile moduli are highest for Lincoln, followed by Chokla and Merino fibers, but there is a reverse trend in the torsional modulus. The differences in mechanical properties are explained in…
Abstract Die Optik gehört zu den ältesten Teilgebieten der Physik und hat zu deren Entwicklung immer wieder entscheidend beigetragen. In der ersten Hälfte dieses Jahrhunderts wurde die Optik durch die aufregenden Entwicklungen in der Quantenmechanik und Elementarteilchenphysik etwas in den Hintergrund (und aus vielen…
Abstract The use of Fe–Mn–Al–C alloys in oxidizing–sulphidizing environments at elevated temperatures is considered. Applications of SEM, EDX mapping and x‐ray diffraction techniques to the microstructural characterization of the scale development on these alloys are reviewed. Combination of the electron microscope an…
Raman-scattering measurements on single crystals of ${\mathrm{K}}_{2}$${\mathrm{SO}}_{4}$, ${\mathrm{Rb}}_{2}$${\mathrm{SO}}_{4}$, and ${\mathrm{Cs}}_{2}$${\mathrm{SO}}_{4}$ have been made at both room and liquid-nitrogen temperatures. Lattice-dynamical calculations, based on a rigid-ion model using the Gordon-Kim met…